Looking at the NOAA HMS Smoke and Fire Product (top left), the small red dots indicate a group of fires in the Midwest. While no notable smoke plumes were seen, the MODIS Terra image (top right) shows corresponding raised AOD values in this area.
The EPA AIRNow combined AQI loop (bottom left) details moderate AQIs across the eastern half of the United States while the West coast had AQIs ranging from moderate to unhealthy throughout the day. The high AQI currently is in Bakersfield, CA (157), but Mississippi even had a very unhealthy AQI early this morning. The OMI NRT tropospheric NO2 column (bottom right) illustrates elevated NO2 in the Midwest, Southwest, and the Northeast, which may help explain the AQIs in these areas. Furthermore, it is consistent with the elevated AODs off of the coast of California and the fires in the Midwest.